Large Hardon Collider

[oldoldman]

Doing physics homework and I'm stuck on a concept question. It's on the photoelectric effect. It tells us that a certain metal with a work function Phi has light incident on it with a flux of 2000Phi/s*cm^2. It asks why that isn't enough info to determine the flux of the electrons coming out. Is it because we would need to know the intensity of the light?

[Kaylia]

Because pulling electrons out of the surface requires a specific amount of energy, knowing the flux isn't enough to determine how much energy hit the surface. You need the wavelength of the photon (or intensity of the beam) for that.

I wouldn't bet my life on this since it's the first time I hear about work function, but what you said sound logical to me. Just make sure that there is no energy unit hidden in Phi however.


[edit]
I will read more about this later tonight or tomorrow, but I need to finish my own paper before.

[Kryssan]

Enthused about this particular news: US DoE agrees to public-private partnerships for SMR deployment development plans

The US Department of Energy (DoE) has announced three public-private partnerships to develop deployment plans for small modular reactor (SMR) technologies at its Savannah River Site (SRS) in South Carolina.

The DoE said that it had signed three separate memorandums of agreement (MoA) with Hyperion Power Generation, NuScale Power and Holtec International's SMR LLC subsidiary. Hyperion has designed a 25 MWe fast reactor, while Holtec and NuScale have designed small pressurized water reactors with capacities of 140 MWe and 45 MWe, respectively.


According to the DoE, the agreements will "help leverage Savannah River's land assets, energy facilities and nuclear expertise to support potential private sector development, testing and licensing of prototype SMR technologies." In addition, they would help private companies to "obtain information on potential SMR reactor siting at Savannah River and provide a framework for developing land use and site services agreements to further these efforts."


The DoE said, "By strengthening information sharing and access to site facilities and technical expertise, these MoAs will help break down engineering and testing barriers to advanced nuclear reactor research and development while providing these nuclear companies with the resources to support effective deployment plans."


Savannah River manager Dave Moody said, "We have a unique combination of nuclear knowledge and laboratory expertise, infrastructure, location and much more to make the site a natural fit for advancing the small modular reactor technology."


However, the DoE stressed that the new agreements "do not constitute a federal funding commitment." It said that it envisages private sector funding to be used to develop these technologies and support deployment plans. The DoE added that the agreements are unrelated to its funding opportunity announcement for SMR cost-share projects announced in January.


Savannah River Nuclear Solutions, which manages SRS on behalf of the DoE, has proposed a demonstration complex with prototype or demonstration models. Hyperion has signed an agreement to build the first and SRNS has approached several other small-reactor developers. The DoE has the authority to build and operate such small reactors if they are not supplying electricity to the grid.


Generically, small modular reactors are seen as offering a number of advantages over typical nuclear plants in various circumstances, such as where grid systems cannot cope with the load from a 1000+ MWe nuclear power plant, or in remote locations. Small reactors are expected to offer greater simplicity of design, economy of mass production, and reduced siting costs. A number of small reactor designs from 25 MWe up to around 300 MWe are in various stages of development around the world.

They're still not going for funding, but at least they're going for it somewhat. I'm a big fan of the SMR ideal for reactor design and implementation, so t'was interesting to me at least.

[Psion]

Sorry to bug the thread with another calculus problem, but I'm honestly not sure how to go about this problem.

Express y" in terms of x and y:

xy = e^y

I think we can use chain rule now, but isn't the derivative of e^something = e^something? I was thinking of doing 1(x)y^0 = e^y for the first derivative, and then 0(y^-1) = e^y for the second, but that doesn't make any sense, and sounds far too simple, which means i know i did it right because calculus is all about making you its bitch with 3 page long answers to a question. besides which, it wouldnt make sense for one side to stay the same while the other changed. So how DOES one express the second derivative of xy = e^y in terms of x and y? I can't find anything in my notes about this, and my book has nothing on it either. ><

[Woozie]

The derivative of d/dx(e^y) = y' d/dy(e^y) = y'*e^y by the chain rule. So

Equation (1): y+xy' = y'e^y
or, solving for y' (I may have made some algebraic errors so you should check my work
Equation (2): y'=1/(e^y-x)

Differentiating equation (1) with respect to x again gives
y' + y' + xy'' = y''e^y + (y')^2 e^y

Solving for y'' gives 2y'-(y')^2 e^y = y''(e^y-x) or y'' = (2y'-(y')^2)e^y/[e^y-x]. Now get rid of each y' by plugging in equation (2) to get your final answer

I'm 100% sure that I made some algebraic errors there so the correct answer will be slightly different than what I have. But you get the general idea of how to solve the problem if you read what I wrote.

Differentiate once to get an expression involving y', y, and x, which I call equation (1).
Solve equation (1) for y' and call this new equation (2)
differentiate equation (1) again (or equation (2) but I think (1) would be simpler to work with. I could be wrong though) and you'll get an expression involving y'', y', y, and x. This can be solved for y''. Get rid of the y' by plugging in your result for equation (2)

[Kryssan]

Superconducting Work Progresses for ITER

More proof at the sheer size of ITER:

Milestones have been reached in the preparatory work for the international next generation fusion reactor, Iter, as Chinese and Italian suppliers complete the construction of key manufacturing facilities and trial versions of parts for the superconducting magnets.

In late February China completed and shipped its first major component for the project - 660 metres of toroidal field dummy conductor; while in Italy in early march the Italian Consortium for Applied Superconductivity (ICAS) completed the commissioning of the jacketing line facility, as well as equipment needed for the manufacturing of conductors.


http://world-nuclear-news.org/upload...on_460x152.jpg
Dummy superconductor coiling being made in Hufei; and offloaded in Fukuoka


The superconducting magnets are some of the highest value and most essential components of the Iter reactor, which is soon to start construction at Cadarache in Southern France. The reactor is to be a kind of tokamak – a doughnut-shaped vacuum vessel which, when operational, will confine and heat a plasma of deuterium and tritium ions to achieve sustained nuclear fusion.



Confinement of the plasma is maintained through the toroidal field system which keeps the plasma moving around the chamber, and a poloidal field which pinches the plasma and keeps it away from the walls. In total Iter will require 16 toroidal field and six poloidal field coils. Each D-shaped toroidal coil contains multiple strands of superconducting cable, and weighs in at about 363 tonnes. Each cable consists of about 1000 strands of a special alloy of niobium and twisted together and encased in a steel jacket.


The 'dummy' version replaces this alloy with copper so as to qualify the cabling and jacketing process without wasting the more valuable superconducting material. In the jacketing process long sections are welded together into a line about 750 metres long and the cable is drawn through it, allowing weld quality to be checked and repaired if necessary.


Member contributions


Twenty kilometres outside of Turin, ICAS – a consortium of ENEA, Tratos Cavi and Criotec – has just completed the commissioning of a facility to fabricate and test superconductor. An 800 metre jacketing platform has been assembled just outside this. The consortium intends to produce three superconducting dummies, with two dummies produced by the end of June this year. ICAS will eventually produce 27 production lengths, measuring approximately 20 kilometres, for the Iter toroidal field coils and will supply jacketing for 22 kilometres worth of the poloidal field coil.


The Chinese dummy magnet conductor was constructed at a facility in Hefei. It reached Fukuoka on 10 March having departed from a port in Shanghai on 26 February. The dummy conductor will be stored at the Wakamatsu site awaiting further processing. This is the first shipment of a major component to be completed component between Iter member countries.


Iter is overseen by seven domestic agencies representing China, the European Union, India, Japan, Russia, South Korea and the United States. It relies upon in-kind contributions from these member agencies for component work packages which have been divided between them. This international scientific collaboration is the largest in the world.



The schedule for the Iter project looks set to be delayed by a year, in part due to the disruptive influence of the natural disasters that struck Japan last March. However the project remains on track to meet costs targets established in an extraordinary meeting in July 2010. The first major part is due to arrive at the site in 2014 and first plasma remains nominally slated for 2019.

At least the major components are starting to roll in now, somewhat.

[Maguspk]

As far as I can tell this is the 'science' thread for BG and this was a great keynote talk by our boy (starts at 6 minutes)

By the way, if China wants to put military bases on Mars we're on Mars in 10 months; you know that, okay. They just have to leak that memo, doesn't even have to be true. We'll take one month to fund, design and build a craft and 9 months to get to Mars, we'll be on Mars in 10 months.

[Hatedregret]

He is such a boss. Couldn't stop watching.

[Pirian]

Thanks, an evening in which I thought I would be studying for finals in a couple weeks, I instead spent watching all the talks NDT has had since the last time I looked up what he's done, and I still have hours and hours left to watch

[Purrrfect]

One of the recent comments to that clip: I used to be an idiot, but then I took a Neil DeGrasse Tyson to the brain.

[Viena]

OP related:

[Cantih]

Here's something interesting.
http://blogs.discovermagazine.com/ba...ldnt-be-there/

But here’s the problem: the galaxy whose light is getting bent has to be on the other side of the cluster, and that cluster is really far away. Note only that, the galaxy has to be bright enough that we can see it at all. Combined, this should make an arc like this rare. Really rare.

So rare, in fact, that it shouldn’t be there at all! The astronomers who did this research worked through the physics and statistics, and what they found is that the odds of seeing this arc in this way are zero. As in, what the heck is it doing there at all?

[Viena]

[Raelia]

Hey, we just fired the LHC. And this is crazy. But we found a new boson. So higgs maybe?

http://webcast.web.cern.ch/webcast/play_higgs.html
You probably missed it.

[Blarg]

I was a fan of the higgs boson before it was discovered but now it has really sold out.

[Blarg]

I see you propelling around tubes like the particle I love and I'm like, forget you

[Mizango]

Fucking stoked in a sense. I have been fascinated with the Higgs for a few years now. As a matter of fact (good luck finding it) but there is a section in here from a few years ago where we were discussing the pros and cons of it being discovered. Still, an exciting ass day.

[Mizango]

Supersymmetry QQ

[Evensong]

I remember that! I still associate the Mizango name with Higgs everytime I see CERN news!

[Zalius]

i am inspired to learn science